ze chen / wave_player

hw

Dependents:   wave_player_mp3 4180_lab2_part9 4180_Lab3_rtos_basic PianoTiles

wave_player.cpp@0:353c78110e44, 2013-07-14 (annotated)

Committer:
zchen311
Date:
Sun Jul 14 20:29:36 2013 +0000
Revision:
0:353c78110e44
done

Who changed what in which revision?

UserRevisionLine numberNew contents of line
zchen311 0:353c78110e44 1 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 2 // a sample mbed library to play back wave files.
zchen311 0:353c78110e44 3 //
zchen311 0:353c78110e44 4 // explanation of wave file format.
zchen311 0:353c78110e44 5 // https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
zchen311 0:353c78110e44 6
zchen311 0:353c78110e44 7 // if VERBOSE is uncommented then the wave player will enter a verbose
zchen311 0:353c78110e44 8 // mode that displays all data values as it reads them from the file
zchen311 0:353c78110e44 9 // and writes them to the DAC. Very slow and unusable output on the DAC,
zchen311 0:353c78110e44 10 // but useful for debugging wave files that don't work.
zchen311 0:353c78110e44 11 //#define VERBOSE
zchen311 0:353c78110e44 12
zchen311 0:353c78110e44 13
zchen311 0:353c78110e44 14 #include <mbed.h>
zchen311 0:353c78110e44 15 #include <stdio.h>
zchen311 0:353c78110e44 16 #include <wave_player.h>
zchen311 0:353c78110e44 17
zchen311 0:353c78110e44 18
zchen311 0:353c78110e44 19 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 20 // constructor -- accepts an mbed pin to use for AnalogOut. Only p18 will work
zchen311 0:353c78110e44 21 wave_player::wave_player(AnalogOut *_dac)
zchen311 0:353c78110e44 22 {
zchen311 0:353c78110e44 23 wave_DAC=_dac;
zchen311 0:353c78110e44 24
zchen311 0:353c78110e44 25 wave_DAC->write_u16(32768); //DAC is 0-3.3V, so idles at ~1.6V
zchen311 0:353c78110e44 26 verbosity=0;
zchen311 0:353c78110e44 27 volumeMod=0;
zchen311 0:353c78110e44 28 }
zchen311 0:353c78110e44 29 int * wave_player:: getVolumeMod()
zchen311 0:353c78110e44 30 {
zchen311 0:353c78110e44 31
zchen311 0:353c78110e44 32 return & volumeMod;
zchen311 0:353c78110e44 33
zchen311 0:353c78110e44 34 }
zchen311 0:353c78110e44 35
zchen311 0:353c78110e44 36 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 37 // if verbosity is set then wave player enters a mode where the wave file
zchen311 0:353c78110e44 38 // is decoded and displayed to the screen, including sample values put into
zchen311 0:353c78110e44 39 // the DAC FIFO, and values read out of the DAC FIFO by the ISR. The DAC output
zchen311 0:353c78110e44 40 // itself is so slow as to be unusable, but this might be handy for debugging
zchen311 0:353c78110e44 41 // wave files that don't play
zchen311 0:353c78110e44 42 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 43 void wave_player::set_verbosity(int v)
zchen311 0:353c78110e44 44 {
zchen311 0:353c78110e44 45 verbosity=v;
zchen311 0:353c78110e44 46 }
zchen311 0:353c78110e44 47
zchen311 0:353c78110e44 48 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 49 // player function. Takes a pointer to an opened wave file. The file needs
zchen311 0:353c78110e44 50 // to be stored in a filesystem with enough bandwidth to feed the wave data.
zchen311 0:353c78110e44 51 // LocalFileSystem isn't, but the SDcard is, at least for 22kHz files. The
zchen311 0:353c78110e44 52 // SDcard filesystem can be hotrodded by increasing the SPI frequency it uses
zchen311 0:353c78110e44 53 // internally.
zchen311 0:353c78110e44 54 //-----------------------------------------------------------------------------
zchen311 0:353c78110e44 55 void wave_player::play(FILE *wavefile,bool *ptr)
zchen311 0:353c78110e44 56 {
zchen311 0:353c78110e44 57 unsigned chunk_id,chunk_size,channel;
zchen311 0:353c78110e44 58 unsigned data,samp_int,i;
zchen311 0:353c78110e44 59 short unsigned dac_data;
zchen311 0:353c78110e44 60 long long slice_value;
zchen311 0:353c78110e44 61 char *slice_buf;
zchen311 0:353c78110e44 62 short *data_sptr;
zchen311 0:353c78110e44 63 unsigned char *data_bptr;
zchen311 0:353c78110e44 64 int *data_wptr;
zchen311 0:353c78110e44 65 FMT_STRUCT wav_format;
zchen311 0:353c78110e44 66 long slice,num_slices;
zchen311 0:353c78110e44 67 DAC_wptr=0;
zchen311 0:353c78110e44 68 DAC_rptr=0;
zchen311 0:353c78110e44 69 for (i=0; i<256; i+=2) {
zchen311 0:353c78110e44 70 DAC_fifo[i]=0;
zchen311 0:353c78110e44 71 DAC_fifo[i+1]=3000;
zchen311 0:353c78110e44 72 }
zchen311 0:353c78110e44 73 DAC_wptr=4;
zchen311 0:353c78110e44 74 DAC_on=0;
zchen311 0:353c78110e44 75
zchen311 0:353c78110e44 76 fread(&chunk_id,4,1,wavefile);
zchen311 0:353c78110e44 77 fread(&chunk_size,4,1,wavefile);
zchen311 0:353c78110e44 78 while (!feof(wavefile)) {
zchen311 0:353c78110e44 79 if (verbosity)
zchen311 0:353c78110e44 80 printf("Read chunk ID 0x%x, size 0x%x\n",chunk_id,chunk_size);
zchen311 0:353c78110e44 81 switch (chunk_id) {
zchen311 0:353c78110e44 82 case 0x46464952:
zchen311 0:353c78110e44 83 fread(&data,4,1,wavefile);
zchen311 0:353c78110e44 84 if (verbosity) {
zchen311 0:353c78110e44 85 printf("RIFF chunk\n");
zchen311 0:353c78110e44 86 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
zchen311 0:353c78110e44 87 printf(" RIFF type 0x%x\n",data);
zchen311 0:353c78110e44 88 }
zchen311 0:353c78110e44 89 break;
zchen311 0:353c78110e44 90 case 0x20746d66:
zchen311 0:353c78110e44 91 fread(&wav_format,sizeof(wav_format),1,wavefile);
zchen311 0:353c78110e44 92 if (verbosity) {
zchen311 0:353c78110e44 93 printf("FORMAT chunk\n");
zchen311 0:353c78110e44 94 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
zchen311 0:353c78110e44 95 printf(" compression code %d\n",wav_format.comp_code);
zchen311 0:353c78110e44 96 printf(" %d channels\n",wav_format.num_channels);
zchen311 0:353c78110e44 97 printf(" %d samples/sec\n",wav_format.sample_rate);
zchen311 0:353c78110e44 98 printf(" %d bytes/sec\n",wav_format.avg_Bps);
zchen311 0:353c78110e44 99 printf(" block align %d\n",wav_format.block_align);
zchen311 0:353c78110e44 100 printf(" %d bits per sample\n",wav_format.sig_bps);
zchen311 0:353c78110e44 101 }
zchen311 0:353c78110e44 102 if (chunk_size > sizeof(wav_format))
zchen311 0:353c78110e44 103 fseek(wavefile,chunk_size-sizeof(wav_format),SEEK_CUR);
zchen311 0:353c78110e44 104 break;
zchen311 0:353c78110e44 105 case 0x61746164:
zchen311 0:353c78110e44 106 // allocate a buffer big enough to hold a slice
zchen311 0:353c78110e44 107 slice_buf=(char *)malloc(wav_format.block_align);
zchen311 0:353c78110e44 108 if (!slice_buf) {
zchen311 0:353c78110e44 109 printf("Unable to malloc slice buffer");
zchen311 0:353c78110e44 110 exit(1);
zchen311 0:353c78110e44 111 }
zchen311 0:353c78110e44 112 num_slices=chunk_size/wav_format.block_align;
zchen311 0:353c78110e44 113 samp_int=1000000/(wav_format.sample_rate);
zchen311 0:353c78110e44 114 if (verbosity) {
zchen311 0:353c78110e44 115 printf("DATA chunk\n");
zchen311 0:353c78110e44 116 printf(" chunk size %d (0x%x)\n",chunk_size,chunk_size);
zchen311 0:353c78110e44 117 printf(" %d slices\n",num_slices);
zchen311 0:353c78110e44 118 printf(" Ideal sample interval=%d\n",(unsigned)(1000000.0/wav_format.sample_rate));
zchen311 0:353c78110e44 119 printf(" programmed interrupt tick interval=%d\n",samp_int);
zchen311 0:353c78110e44 120 }
zchen311 0:353c78110e44 121
zchen311 0:353c78110e44 122 // starting up ticker to write samples out -- no printfs until tick.detach is called
zchen311 0:353c78110e44 123 if (verbosity)
zchen311 0:353c78110e44 124 tick.attach_us(this,&wave_player::dac_out, 500000);
zchen311 0:353c78110e44 125 else
zchen311 0:353c78110e44 126 tick.attach_us(this,&wave_player::dac_out, samp_int);
zchen311 0:353c78110e44 127 DAC_on=1;
zchen311 0:353c78110e44 128
zchen311 0:353c78110e44 129 // start reading slices, which contain one sample each for however many channels
zchen311 0:353c78110e44 130 // are in the wave file. one channel=mono, two channels=stereo, etc. Since
zchen311 0:353c78110e44 131 // mbed only has a single AnalogOut, all of the channels present are averaged
zchen311 0:353c78110e44 132 // to produce a single sample value. This summing and averaging happens in
zchen311 0:353c78110e44 133 // a variable of type signed long long, to make sure that the data doesn't
zchen311 0:353c78110e44 134 // overflow regardless of sample size (8 bits, 16 bits, 32 bits).
zchen311 0:353c78110e44 135 //
zchen311 0:353c78110e44 136 // note that from what I can find that 8 bit wave files use unsigned data,
zchen311 0:353c78110e44 137 // while 16 and 32 bit wave files use signed data
zchen311 0:353c78110e44 138 //
zchen311 0:353c78110e44 139 for (slice=0; slice<num_slices; slice+=1) {
zchen311 0:353c78110e44 140 if(*ptr==0)
zchen311 0:353c78110e44 141 break;
zchen311 0:353c78110e44 142 fread(slice_buf,wav_format.block_align,1,wavefile);
zchen311 0:353c78110e44 143 if (feof(wavefile)) {
zchen311 0:353c78110e44 144 printf("Oops -- not enough slices in the wave file\n");
zchen311 0:353c78110e44 145 exit(1);
zchen311 0:353c78110e44 146 }
zchen311 0:353c78110e44 147 data_sptr=(short *)slice_buf; // 16 bit samples
zchen311 0:353c78110e44 148 data_bptr=(unsigned char *)slice_buf; // 8 bit samples
zchen311 0:353c78110e44 149 data_wptr=(int *)slice_buf; // 32 bit samples
zchen311 0:353c78110e44 150 slice_value=0;
zchen311 0:353c78110e44 151 for (channel=0; channel<wav_format.num_channels; channel++) {
zchen311 0:353c78110e44 152 switch (wav_format.sig_bps) {
zchen311 0:353c78110e44 153 case 16:
zchen311 0:353c78110e44 154 if (verbosity)
zchen311 0:353c78110e44 155 printf("16 bit channel %d data=%d ",channel,data_sptr[channel]);
zchen311 0:353c78110e44 156 slice_value+=data_sptr[channel];
zchen311 0:353c78110e44 157 break;
zchen311 0:353c78110e44 158 case 32:
zchen311 0:353c78110e44 159 if (verbosity)
zchen311 0:353c78110e44 160 printf("32 bit channel %d data=%d ",channel,data_wptr[channel]);
zchen311 0:353c78110e44 161 slice_value+=data_wptr[channel];
zchen311 0:353c78110e44 162 break;
zchen311 0:353c78110e44 163 case 8:
zchen311 0:353c78110e44 164 if (verbosity)
zchen311 0:353c78110e44 165 printf("8 bit channel %d data=%d ",channel,(int)data_bptr[channel]);
zchen311 0:353c78110e44 166 slice_value+=data_bptr[channel];
zchen311 0:353c78110e44 167 break;
zchen311 0:353c78110e44 168 }
zchen311 0:353c78110e44 169 }
zchen311 0:353c78110e44 170 slice_value/=wav_format.num_channels;
zchen311 0:353c78110e44 171
zchen311 0:353c78110e44 172 // slice_value is now averaged. Next it needs to be scaled to an unsigned 16 bit value
zchen311 0:353c78110e44 173 // with DC offset so it can be written to the DAC.
zchen311 0:353c78110e44 174 switch (wav_format.sig_bps) {
zchen311 0:353c78110e44 175 case 8:
zchen311 0:353c78110e44 176 slice_value<<=8;
zchen311 0:353c78110e44 177 break;
zchen311 0:353c78110e44 178 case 16:
zchen311 0:353c78110e44 179 slice_value+=32768;
zchen311 0:353c78110e44 180 break;
zchen311 0:353c78110e44 181 case 32:
zchen311 0:353c78110e44 182 slice_value>>=16;
zchen311 0:353c78110e44 183 slice_value+=32768;
zchen311 0:353c78110e44 184 break;
zchen311 0:353c78110e44 185 }
zchen311 0:353c78110e44 186 dac_data=(short unsigned)slice_value;
zchen311 0:353c78110e44 187 if (verbosity)
zchen311 0:353c78110e44 188 printf("sample %d wptr %d slice_value %d dac_data %u\n",slice,DAC_wptr,(int)slice_value,dac_data);
zchen311 0:353c78110e44 189 DAC_fifo[DAC_wptr]=dac_data;
zchen311 0:353c78110e44 190 DAC_wptr=(DAC_wptr+1) & 0xff;
zchen311 0:353c78110e44 191 while (DAC_wptr==DAC_rptr) {
zchen311 0:353c78110e44 192 }
zchen311 0:353c78110e44 193 }
zchen311 0:353c78110e44 194 DAC_on=0;
zchen311 0:353c78110e44 195 tick.detach();
zchen311 0:353c78110e44 196 free(slice_buf);
zchen311 0:353c78110e44 197 break;
zchen311 0:353c78110e44 198 case 0x5453494c:
zchen311 0:353c78110e44 199 if (verbosity)
zchen311 0:353c78110e44 200 printf("INFO chunk, size %d\n",chunk_size);
zchen311 0:353c78110e44 201 fseek(wavefile,chunk_size,SEEK_CUR);
zchen311 0:353c78110e44 202 break;
zchen311 0:353c78110e44 203 default:
zchen311 0:353c78110e44 204 printf("unknown chunk type 0x%x, size %d\n",chunk_id,chunk_size);
zchen311 0:353c78110e44 205 data=fseek(wavefile,chunk_size,SEEK_CUR);
zchen311 0:353c78110e44 206 break;
zchen311 0:353c78110e44 207 }
zchen311 0:353c78110e44 208 fread(&chunk_id,4,1,wavefile);
zchen311 0:353c78110e44 209 fread(&chunk_size,4,1,wavefile);
zchen311 0:353c78110e44 210 }
zchen311 0:353c78110e44 211 }
zchen311 0:353c78110e44 212
zchen311 0:353c78110e44 213
zchen311 0:353c78110e44 214 void wave_player::dac_out()
zchen311 0:353c78110e44 215 {
zchen311 0:353c78110e44 216
zchen311 0:353c78110e44 217 if (DAC_on) {
zchen311 0:353c78110e44 218 #ifdef VERBOSE
zchen311 0:353c78110e44 219 printf("ISR rdptr %d got %u\n",DAC_rptr,DAC_fifo[DAC_rptr]);
zchen311 0:353c78110e44 220 #endif
zchen311 0:353c78110e44 221
zchen311 0:353c78110e44 222 wave_DAC->write_u16(DAC_fifo[DAC_rptr] * (16 - volumeMod)>>4);
zchen311 0:353c78110e44 223
zchen311 0:353c78110e44 224 DAC_rptr=(DAC_rptr+1) & 0xff;
zchen311 0:353c78110e44 225 }
zchen311 0:353c78110e44 226
zchen311 0:353c78110e44 227
zchen311 0:353c78110e44 228 }
zchen311 0:353c78110e44 229